Large trucks may be provided by an original manufacturer having certain dimensions, including a standard cab height dimension. A manufacturer may wish to offer the truck or an owner of such a truck may wish to use the truck as a vocational truck such as an automobile hauler, a utility truck or the like. In some cases, the truck can not be readily put to such use because the standard cab height does not provide for sufficient overhead clearance for a body structure, vocational equipment or the like.